Implementation of high definition television (HDTV) in the U.S. is now undergoing testing by the Federal Communications Commission. It is contemplated that such an HDTV system will require additional channel allocations on UHF frequencies which will carry a digital signal. Thus alterations to existing transmitting antennas will be required. The existing TV signal is normally designated an NTSC signal which is analog. It is contemplated that the HDTV digital signal will be located on the same transmission tower. However, because of the normal NTSC signal is in the VHF frequency range, such VHF antenna cannot simultaneously serve UHF channels. In such cases, the HDTV operation will require a separate antenna in a different location of the tower.
Since the physical location of an antenna on a transmitting tower used by several TV stations is quite critical, to locate the HDTV antenna on another part of the tower, or even relocate the entire antenna installation is not desirable.